How much should the catalytic cracking stripping steam be controlled at?
Thread Content
According to the operating procedures for catalytic cracking, the stripping steam in the stripping section is specified to be 3% of the feed volume; however, I have seen some sources state that for heavy oil catalytic cracking, the stripping steam should be controlled at 4-5%. So, what level of control is appropriate? Too high a level can lead to the hydrothermal deactivation of the catalyst, while too low a level results in insufficient stripping and an excessive amount of coke formation.
The stripping steam level should be controlled at 4-5%; a higher level is better than a lower one
Experience-based guidance: The ideal amount of stripping steam for typical catalytic cracking reactions is 2 kg per ton of catalyst; exceeding this amount yields little benefit and increases energy consumption, but it should not be less than 1 kg per ton of catalyst.
Adjust the amount of stripping steam to ensure that the catalyst density in the stripping section remains no greater than 700 kg/m3.
We keep it around 3.5% here
The method we use to control the amount of stripping steam is to keep it at around 4%, then adjust this amount slightly to see if there is any change in the dense-phase temperature of the regenerator, and finally fix that amount of steam
1# hlytyy: The theoretical steam amount for stripping is 1~2 Kg/t of catalyst. In practice, an appropriate amount of stripping steam can be determined through trial and error. Method: By gradually reducing the amount of stripping steam, when the regeneration temperature rises, that amount of stripping steam represents the minimum required level; the actual amount used can be 1.1 times this minimum value.
It should be related to the properties of the raw materials; in actual production, both methods can be tried to compare the results
In the stripping section, it is first necessary to maintain an appropriate temperature for the steam; too low a temperature can affect the catalyst. As for the amount of steam used, it is important to understand that the purpose of using steam here is to displace the oil and gas present in the raw catalyst, thereby increasing the yield of the product, reducing energy consumption, and minimizing the burning load on the regenerator. When adjusting the amount of steam, it is sufficient to ensure that the temperature of the dense phase bed in the regenerator does not rise any further – there is no need to increase the steam volume further. As for determining what percentage of steam should be used, I believe it isn’t very meaningful; as long as the optimal results are achieved, that’s all that matters.
There are two sets of equipment in the plant; one uses low-pressure steam at 1.0 MPA, while the other uses medium-pressure superheated steam at 3.5 MPA. Due to differences in temperature, the amount used must vary.
Depending on the structure of the stripping section, the amount of stripping steam is generally 0.2-0.4% (by weight) of the catalyst circulation rate. At the same time, based on the bed temperature, the amount of stripping steam is increased until the bed temperature no longer decreases as it rises. It is not advisable to produce too much steam, as this wastes energy.